DXT-MAX - Small active monitors

[silverD]

Thanks Steve, I felt that this would be a great opportunity to start experimenting with active crossovers. I'm new to active crossovers, but with the winter months coming it will provide some easy tinkering. David, yes the baffles will remain natural. The two coats of shellac I put on seem to have done a decent job of sealing the end grain. I was thinking of brush/roller applying a shellac-based primer and then top coating with a matte paint. Was at first thinking a gray but now I might look to a lighter color. Wolf, do you think the epoxy is necessary after shellac and shellac primer?

[djg]

If you're rolling it on, consider latex wall paint. A gazillion colors, super thick, all sorts of roller textures.

[silverD]

I assembled the second one, lined it with foam like the other, added 60 grams this time to the PR, and didn't use any Acousta-Stuf. These are over 20lbs each!

[Wolf]

As long as it's sealed and impervious, you should be fine.

Wolf

[silverD]

I'm thinking I'll go white for the cabs while keeping the baffle natural. Rolling or sprayed, I hope to give them some texture to help hide any blemishes. Here is a screenshot of the crossover in SigmaStudio and everything connected an running! I opted to swap in an Icepower 125asx2 amp with volume control for the tweeters to make the level matching easier and on the fly. They stack nice as well.

[djg]

You may never paint them. They look nice. you might want to make short stands to get them up off the desktop.

The baffles on the Schumakubins HT suite was Rustoleum stone texture.

https://duckduckgo.com/?q=rust+oleum+textured+spray+paint&t=ffab&atb=v187-1&iar=images&iax=images&ia=images

[silverD]

You might be right, they might not see a color change. If they stay on the table/desk, I'll look into stands. Those foam wedges may not cut it for these heavyweights. I used the stone texture spray paint for the TriTrix I rehabbed. Sprayed over with the final paint color I wanted.

[Steve Lee]

Sweet!!

I love Sigma studio programming.

How are they sounding and what are the XO details?

[silverD]

The crossover in the pic above is what I came up with as I was building the speakers:
DC blocking -> 4dB baffle step @ 600 Hz -> X-over LR48 @ 1800Hz -> split into 4 channels -> LF PEQ of 20Hz high pass / No HF PEQ yet -> gain adjustment for tweeters not in use yet.

[silverD]

Changed the x-over slope from LR8-48dB to LR4-24dB to match that of the DXT-MON and added a LF PEQ @ 30Hz:

[Steve Lee]

^ This is what I really like about DSP.

I still think passives are the best solution in the long run though . . .

[silverD]

The extra low end boost helped fill in the lowest notes. The healthy xmax allows for this type of EQ with DSP. So far the listening has been in a small room near field and these provide plenty of bass. I need to look at the overall FR and adjust accordingly, but they sound good so far with great imaging.

[tomzarbo]

Thanks for the comments everyone

Tom, I'd have to pull up the WinISD model on other computer, but I think at 70W/100dB both the woofer and PR (with 30g mass added) are under xmax with a HPF at 20Hz.

I'm so sorry, I modeled the PR with an older Esoteric woofer, not the Epique 5 1/2" sub, my mistake!
Just wanted to clear this up to avoid any future confusion.

TomZ

[Scarface1]

Is there any progress made the last weeks? Really curious how they sound

[silverD]

Hi Scarface,
Besides the tweaks above, I tinkered with some filters for the tweeter. I'm still learning to take measurements and I don't have a dedicated space to take them. Throw in the fact I have a two year old and it makes it difficult to get space and time to tinker. I think they sound great, but do not have a trained ear. I do notice more hiss than I would like out of the tweeter vs a passive speaker, so I'm looking to change up my DSP a bit. I was running a chromecast audio -> optical -> SMSL SK 10th -> analog -> DSP board (ADC -> DSP -> DAC) -> amps so I thought removing the extra ADC/DAC would help. I connected a pi running Moode to the DSP board via i2s and while it helped some, there is still some hiss. I was looking at the miniDSP nanoDIGI, but they're are no longer being made.

[Scarface1]

Hi Scarface,
Besides the tweaks above, I tinkered with some filters for the tweeter. I'm still learning to take measurements and I don't have a dedicated space to take them. Throw in the fact I have a two year old and it makes it difficult to get space and time to tinker. I think they sound great, but do not have a trained ear. I do notice more hiss than I would like out of the tweeter vs a passive speaker, so I'm looking to change up my DSP a bit. I was running a chromecast audio -> optical -> SMSL SK 10th -> analog -> DSP board (ADC -> DSP -> DAC) -> amps so I thought removing the extra ADC/DAC would help. I connected a pi running Moode to the DSP board via i2s and while it helped some, there is still some hiss. I was looking at the miniDSP nanoDIGI, but they're are no longer being made.

I want to build something with the e150 and a dsp amp myself so i'm really curious how it turn out for you. You can buy pre-amp DSP boards like the miniDSP 4x2 or a dayton DSPB-K ( this one is cheap but if it do the job i wanna use it because it's small AND cheaper )

Have you tried a simple filter or no filter at all for the tweeter, maybe it's not the amp or other equipement but just the filter in dsp. I had some issues with the sound while using dsp and when i re-write the same dsp filters on the chip it got away.

[silverD]

The cheapest miniDSP uses a similar ADAU chip to the DSPB-K which is essentially what I'm currently using but also has opamps on the outputs. The amp powering the tweeter is an Icepower 125asx2 which has a CMoy preamp after the volume pot. I'm looking to utilize a 50asx2SE without preamp or volume in the near future and we'll see if this helps. I have made some changes to the filters, but your suggestion is a good one.

[a4eaudio]

Tom, I'd have to pull up the WinISD model on other computer, but I think at 70W/100dB both the woofer and PR (with 30g mass added) are under xmax with a HPF at 20Hz.

I'm so sorry, I modeled the PR with an older Esoteric woofer, not the Epique 5 1/2" sub, my mistake!

Tom, SilverD - did you guys find the xmax for the SB passive radiator somewhere? I can't find it, but I'm thinking that twice the xmax of the matching woofer would make sense.

SilverD - Now that you've had some more time to listen to these, did you make any more tweaks? Regardless of tweeter, any reservations on recommending the E150HE for small two-way builds?